18000209 has 2 divisors, whose sum is σ = 18000210. Its totient is φ = 18000208.

The previous prime is 18000149. The next prime is 18000217. The reversal of 18000209 is 90200081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16851025 + 1149184 = 4105^2 + 1072^2 .

It is an emirp because it is prime and its reverse (90200081) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18000209 - 2⁸ = 17999953 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18000259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9000104 + 9000105.

It is an arithmetic number, because the mean of its divisors is an integer number (9000105).

Almost surely, 2^18000209 is an apocalyptic number.

It is an amenable number.

18000209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18000209 is an equidigital number, since it uses as much as digits as its factorization.

18000209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 18000209 is about 4242.6653179340. The cubic root of 18000209 is about 262.0751537409.

The spelling of 18000209 in words is "eighteen million, two hundred nine", and thus it is an aban number.